As the material of resistance change elements (resistance change layers) provided in a nonvolatile semiconductor memory device (ReRAM, resistance change memory), carbon-based nanomaterials (hereinafter simply referred to as carbon nanomaterials) such as carbon nanotubes and fullerenes are under study.
Here, the resistance change layer including a carbon nanomaterial has interstices in its structure. Thus, when electrodes are formed so as to sandwich the resistance change layer, the interstices of the resistance change layer may be filled with a conductor substance, which may cause short circuit between the electrodes. The following problem arises in this case. If short circuit occurs between the electrodes sandwiching the resistance change layer, no voltage can be applied to the resistance change layer, and no resistance change can be produced.
Furthermore, with the decrease of film thickness of the resistance change layer, the distance between the electrodes is made shorter, and short circuit is more likely to occur. This makes it difficult to reduce the thickness of the resistance change layer and increase the integration density of the nonvolatile semiconductor memory device. Furthermore, interstices occur between carbon nanomaterials, and hence decrease the contact area between the resistance change layer and the electrode. Thus, the adhesiveness therebetween is made insufficient, which may increase the danger of peeling. In addition, the decreased contact area between the resistance change layer and the electrode may increase the contact resistance.